U.S. patent number 4,009,591 [Application Number 05/646,196] was granted by the patent office on 1977-03-01 for single evaporator, single fan combination refrigerator with independent temperature controls.
This patent grant is currently assigned to General Electric Company. Invention is credited to William F. Hester.
United States Patent |
4,009,591 |
Hester |
March 1, 1977 |
**Please see images for:
( Certificate of Correction ) ** |
Single evaporator, single fan combination refrigerator with
independent temperature controls
Abstract
A single evaporator, single fan combination refrigerator
includes a temperature control system which thermostatically
maintains the fresh food compartment at a desired temperature by
cycling the refrigerator system on and off as required, and which
controls freezer compartment temperature by varying airflow through
a duct conducting refrigerated air from the evaporator chamber to
the fresh food compartment. Variable airflow control apparatus
comprising a mechanical summer operating an air valve varies
airflow through the duct as a function of the settings of both the
fresh food control and the freezer control.
Inventors: |
Hester; William F. (Louisville,
KY) |
Assignee: |
General Electric Company
(Louisville, KY)
|
Family
ID: |
24592152 |
Appl.
No.: |
05/646,196 |
Filed: |
January 2, 1976 |
Current U.S.
Class: |
62/180; 62/455;
62/187 |
Current CPC
Class: |
F25D
17/045 (20130101); F25D 17/065 (20130101); F24F
11/81 (20180101); F25D 2400/06 (20130101) |
Current International
Class: |
F25D
17/04 (20060101); F24F 11/02 (20060101); F25D
17/06 (20060101); F25D 017/00 () |
Field of
Search: |
;62/180,187,455 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wayner; William E.
Assistant Examiner: Charvat; R. J.
Attorney, Agent or Firm: Schnedler; Steven C. Boos; Francis
H.
Claims
What is claimed is:
1. A refrigerator comprising:
a. a freezer compartment;
b. a fresh food compartment;
c. an evaporator chamber and an evaporator in said chamber;
d. an air circulation system including a fan and passageways for
circulating air from both of said compartments through said
evaporator chamber, a passageway for conducting a first stream of
air from said evaporator chamber to said freezer compartment, and a
duct for conducting a second stream of air from said evaporator
chamber to said fresh food compartment;
e. a thermostatic control for maintaining a desired temperature in
said fresh food compartment by causing energization of said
evaporator as required, said thermostatic control including an
element for sensing temperature in said fresh food compartment;
f. a first user-operable control member for setting a desired
temperature to be maintained in said freezer compartment;
g. a second user-operable control member for setting the desired
temperature to be maintained in said fresh food compartment, said
second user-operable control member being operatively connected to
said thermostatic control; and
h. variable airflow control apparatus for varying airflow through
said duct as a function of the settings of both of said
user-operable control members, said apparatus including:
i. an adjustable air valve for controlling airflow through said
duct; and
ii. a mechanical summer having a main input connected to said first
user-operable control member, a compensating input connectd to said
second user-operable control member, and an output operatively
connected to said air valve, the connection to said air valve being
such that the degree of opening of said air valve is a direct
function of the temperature setting of said first user-operable
control member and an inverse function of the temperature setting
of said second user-operable control member, said function being
selected so that the desired temperature is approximately
maintained in said freezer compartment even though the setting of
said second user-operable control member is changed.
2. A refrigerator according to claim 1, wherein said mechanical
summer comprises:
a. a driven pinion gear including an axle, said pinion gear and
axle having a common axis which is movable along a line;
b. first and second racks engaging said pinion gear on
diametrically opposite sides such that the position of said pinion
gear axis represents the sum of the longitudinal displacements of
said first and second racks;
c. output means for controlling the degree of opening of said air
valve in response to the position of said pinion gear axis;
d. first and second driving gears connected to said first and
second user-operable control members and engaging said first and
second racks to cause longitudinal displacement thereof in response
to operation of said control members.
3. A refrigerator according to claim 2, wherein said output means
comprises a slotted yoke member having a slot engaging said pinion
gear axle.
4. A refrigerator according to claim 2, wherein the movement of the
pinion gear axis is limited to prevent said user-operable control
members from being set to a combination of freezer and fresh food
temperatures which is not within the capabilities of the
refrigerator.
5. A refrigerator according to claim 2, wherein said second driving
gear and said second rack include lost motion gearing to permit
said second user-operable control member and thus said thermostatic
control to be moved to an OFF position.
6. A refrigerator according to claim 1, wherein said mechanical
summer comprises:
a. a driving ring gear firmly attached to one of said
manually-operable control members and rotatable therewith about a
major axis;
b. a driving central gear located within said ring gear, coaxially
therewith, and having a shaft extending along the major axis and
connected to the other one of said user-operable control
members;
c. a pinion gear engaging both said ring gear and said central
gear, said pinion gear having an axle movable in an accurate
path;
d. a pinion gear carrier engaging said axle and serving as the
output of said summer.
Description
CROSS REFERENCE TO RELATED APPLICATION
The present invention is partly disclosed, but not claimed, in
copending application Ser. No. 646,167, filed Jan. 2, 1976,
concurrently herewith, by William M. Webb and William F. Hester,
also entitled SINGLE EVAPORATOR, SINGLE FAN COMBINATION
REFRIGERATOR WITH INDEPENDENT TEMPERATURE CONTOLS, and assigned to
the same assignee as the present invention.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to household refrigerators and more
particularly to a temperature control system for a single
evaporator, single fan type combination refrigerator including
independent freezer compartment and fresh food compartment
temperature controls.
2. Description of the Prior Art
Combination refrigerators of the "frost free" type including a
single evaporator and a single fan for circulating air from the
freezer and the fresh food compartments over the evaporator are
well known. Examples are disclosed in U.S. Pat. No.
3,126,177--Schumacher and in U.S. Pat. No. 3,320,761--Gelbard. In
such refrigerators, a major portion (approximately 90%) of the
refrigerated air from the evaporator is directed through a
passageway into the freezer compartment while a smaller portion
(approximately 10%) is directed through a duct into the fresh food
compartment. Two user-operable temperature control members are
provided. One control member is for setting a temperature to be
maintained in the fresh food compartment and is typically called
either the "fresh food control" or "cold control." The fresh food
control dial has graduations from "1" through "9," "1" indicating
the warmest temperature and 9 indicating the coldest temperature to
be set. The other control member is primarily for determining a
preset temperature to be maintained in the freezer compartment and
is typically called the "freezer control." The freezer control has
graduations from A through E, with E being the coldest
position.
The fresh food control is operatively connected to a thermostatic
control which senses either fresh food compartment air temperature
or a mixture of compartment air and incoming refrigerated air from
the evaporator and thermostatically maintains the fresh food
compartment temperature near the desired temperature by
periodically energizing and de-energizing the refrigeration
compressor, and thus the evaporator, in a conventional manner.
Usually, the fan is energized and de-energized along with the
evaporator. The thermostatic control causes energization of the
evaporator when the fresh food compartment temperature exceeds the
temperature setting of the fresh food control and causes
de-energization of the evaporator when the fresh food compartment
temperature is less than the temperature setting of the fresh food
control.
The freezer control is connected in simple fashion to an air flow
damper positioned in the duct which carries refrigerated air from
the evaporator chamber to the fresh food compartment. In operation,
as the freezer control is moved toward E, or the coldest position,
the damper is closed more, reducing the amount of refrigerated air
flowing into the fresh food compartment. Since the temperature in
the fresh food compartment is thermostatically controlled, the
compressor, under control of the thermostatic control simply runs
longer or more often to satisfy the requirements of the fresh food
compartment. When the compressor and evaporator run more, more
refrigerated air flows into the freezer compartment for a longer
period of time and the freezer compartment gets colder. Conversely,
as the freezer control is moved toward A, or the warmest position,
the damper is opened more, allowing more refrigerated air from the
evaporator chamber to flow through the duct into the fresh food
compartment. This causes the compressor and the evaporator to be
energized less frequently or for shorter periods of time to satisfy
the cooling requirements of the fresh food compartment. Since the
temperature in the freezer compartment is directly related to the
percentage of compressor and evaporator "on" time, the temperature
in the freezer compartment decreases.
To summarize the above, in prior art refrigerators the temperature
in the fresh food compartment is thermostatically controlled by
energizing the compressor and evaporator in response to the cooling
requirements of the fresh food compartment. Being under actual
thermostatic control, the temperature is maintained quite
efficiently at approximately the desired temperature. The
temperature in the freezer compartment is not thermostatically
controlled, but rather is controlled by varying the flow of
refrigerated air from the evaporator chamber to the fresh food
compartment, thereby forcing the compressor and evaporator to run
for either longer or shorter periods of time to satisfy the
requirements of the fresh food compartment, indirectly affecting
the temperature in the freezer compartment.
Temperature control systems of the above-described type, while
inexpensive and relatively effective, have the disadvantage that
the fresh food and freezer controls do not exert truly independent
control over the temperatures of the two compartments. The
interaction between the temperature controls contributes
significantly to customer dissatisfaction and costly complaints. In
actual operation, the fresh food control, in addition to desirably
setting a temperature to be thermostatically maintained in the
fresh food compartment, undesirably affects the temperature of the
freezer compartment. This undesirable effect is a direct result of
the fact that, as the setting of the fresh food control is varied,
in order to satisfy the cooling requirements of the fresh food
compartment as determined by the fresh food control setting, the
percentage of compressor and evaporator run time also varies. For
example, if the compressor runs longer to maintain the fresh food
compartment at a lower desired temperature, the freezer temperature
also is lowered. The freezer control actually operates as a
temperature differential control to maintain the freezer
compartment temperature at a given temperature below the fresh food
compartment temperature, the given temperature being determined by
the setting of the freezer control. If the fresh food control
setting is not disturbed, then the freezer control actually does
control the temperature in the freezer. However, if the fresh food
control setting is changed, with no change in the freezer control
setting, the temperature differential between the two compartments
is approximately maintained and the temperature in the freezer
compartment undesirably goes up or down, depending upon the desired
temperature change in the fresh food compartment.
Control interaction in the opposite direction, that is, fresh food
compartment temperature variations as a result of changes in the
setting of the freezer control, are not a significant problem
because fresh food compartment temperature is substantially
thermostatically maintained.
A further disadvantage which follows from the basic disadvantage of
control interaction is that it is impossible to calibrate the
freezer control directly in temperature. Any calibration of the
freezer control directly in temperature would be valid only for a
particular setting of the fresh food control.
Despite these disadvantages, the above-described prior art system
enjoys wide use due to its relative simplicity and low cost. This
points up the strict requirement that any improved system, to be
practical, must also be relatively simple and low in cost.
A simple approach to the problem would be explaining to the user of
the refrigerator the need to readjust the freezer control every
time the setting of the fresh food control is changed. An astute
user could adjust the controls to maintain the temperatures he
desired in both compartments. The labeling of the "fresh food
control" as a "cold control" in some refrigerator models is a step
in this direction. However, there are problems in such an approach.
A refrigerator with controls which appear complex to operate might
be more difficult to sell. In the same vein, a detailed explanation
might only serve to point out to a potential customer just how much
undesirable control interaction there is. Further, many users
either would not fully understand an explanation or would simply
choose to ignore it.
It is known to mechanically overcome the above-described
interactive control problem by thermostatically adjusting the
damper in the duct carrying refrigerated air from the evaporator
chamber to the fresh food compartment. In such a system, employing
what is termed a "thermal damper," the freezer control does not
control the damper directly, but rather is connected to a
thermostatic control which senses the temperature in the freezer
compartment. The control adjusts the damper opening in response to
both the freezer compartment temperature and the control setting to
thermostatically maintain the freezer compartment temperature.
Although such a system works well, it suffers the disadvantage of
added complexity with attendant higher cost and greater possibility
of failure in use.
Another known way to achieve truly independent temperature control
for the fresh food and freezer compartment is to provide separate
thermostatically controlled fans for directing refrigerated air
from the evaporator chamber to each of the compartments. Each of
the fans is controlled in response to a thermostatic control
located in the corresponding compartment. Such a system is
disclosed in U.S. Pat. No. 3,005,321--Devery. While this system
also should effectively provide independent control of the
temperatures in the two compartments, it too suffers the
disadvantage of complexity. Further, it would require extensive
changes to existing refrigerator designs to implement it.
The above-mentioned copending Webb and Hester application Ser. No.
646,167 discloses and claims a generic refrigerator temperature
control system which overcomes the problem of control interaction
to provide truly independent control over freezer and fresh food
compartment temperature. That system conventionally includes
apparatus which varies airflow through the duct as a direct
function of the setting of the freezer control. Additionally, in
order to compensate for undesired changes in freezer temperature
which would otherwise result when the setting of the fresh food
control is changed, the variable airflow apparatus has an input
ganged to the fresh food control and varies airflow as an inverse
function of the setting of the fresh food control.
The present invention provides specific embodiments of variable
airflow apparatus which controls duct airflow as the desired
function of the settings of the two control members.
SUMMARY OF THE INVENTION
A refrigerator, according to the present invention, in one
embodiment thereof is an improvement of a refrigerator of the type
generally comprising: a freezer compartment; a fresh food
compartment; an evaporator in an evaporator chamber; and an air
circulation system including a fan, passageways for circulating air
from both of the compartments through the evaporator chamber, a
passageway for conducting a first stream of air from the evaporator
chamber to the freezer compartment, and a duct for conducting a
second stream of air from the evaporator chamber to the fresh food
compartment. The refrigerator also includes a first user-operable
control member for setting a desired temperature to be maintained
in the freezer compartment, designated the "freezer control," and a
second user-operable control member for setting a second desired
temperature to be maintained in the fresh food compartment. As is
conventional, the second user-operable control member is designated
the "fresh food control" and is operatively connected to a
thermostatic control which includes an element for sensing fresh
food compartment temperature and which controls the energization of
the evaporator to approximately maintain the second preset
temperature in the fresh food compartment.
In accordance with the invention, the refrigerator further includes
variable air flow control apparatus for varying the flow of
refrigerated evaporator chamber air through the duct into the fresh
food compartment. The variable air flow apparatus comprises an
adjustable air valve and a mechanical summer having an output
operatively connected to the air valve. A main input of the
mechanical summer is connected to the freezer control and a
compensating input is connected to the fresh food control, for
ganged operation with the thermostatic control. The arrangement is
such that when the freezer control setting is changed to call for a
lower temperature to be maintained in the freezer compartment, duct
airflow is decreased, and when the freezer control setting is
changed to call for a higher temperature to be maintained in the
freezer compartment, duct airflow is increased. In order to
compensate for undesirable variations in freezer compartment
temperature, when the setting of the fresh food control is changed
to call for a lower temperature to be maintained in the fresh food
compartment, duct airflow is increased, and when the fresh food
control setting is changed to call for a higher temperature to be
maintained in the fresh food compartment, duct airflow is
decreased.
In operation, as the thermostatic fresh food compartment
temperature control is manually changed to call, for example, for a
higher temperature, the compressor and evaporator, as outlined in
the "Background of the Invention," operate less frequently and the
fresh food temperature desirably decreases. If no compensation were
provided, then the temperature of the freezer compartment would
also increase, undesirably. The compensation which the present
invention provides through the mechanical summer including a
compensating input connected to the fresh food control and an
output connected to the adjustable air valve, overcomes the
undesirable effect.
BRIEF DESCRIPTION OF THE DRAWINGS
While the novel features of the invention are set forth with
particularity in the appended claims, the invention, both as to
organization and content, will be better understood and
appreciated, along with other objects and features thereof, from
the following detailed description taken in conjunction with the
drawings, in which:
FIG. 1 is a schematic representation of a refrigerator having a
prior art temperature control system.
FIG. 2 is a graphical illustration of the temperature control
characteristic curve for the control system included in a
refrigerator shown in FIG. 1.
FIG. 3 is a graphical illustration of an optimum temperature
control characteristic curve.
FIG. 4 is a graphical illustration of a temperature control
characteristic curve which is within the operating limits of the
refrigeration system of the prior art refrigerator shown in FIG.
1.
FIG. 5 is a schematic representation of the duct portion of a
refrigerator including one embodiment of the invention.
FIG. 6 is a perspective view of a portion of another embodiment of
the present invention.
FIG. 7 is a perspective view of a portion of still another
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 1, there is illustrated, in schematic form,
essential elements of a prior art single evaporator, single fan
combination refrigerator 20 as typified by the refrigerators
disclosed in the above-mentioned U.S. Pat. Nos.
3,126,717--Schumacher and 3,320,761--Gelbard. It is believed that
the present invention and the operation thereof will be better
understood with reference to the prior art refrigerator 20 which
the invention improves. A description of the prior art refrigerator
20 therefore follows.
The refrigerator 20 generally comprises an insulated outer wall 22
defining a freezer compartment 24 and a fresh food compartment 26.
The two compartments are separated by an insulated partition 28. An
evaporator 30 for refrigerating the compartments 24 and 26 is
contained within an evaporator chamber 32. It will be understood
that the refrigerator 20 includes a conventional closed refrigerant
circuit (not shown) for energizing the evaporator 30, the
refrigerant circuit comprising the usual compressor, condenser, and
flow restricting capillary tube. It will further be understood that
a conventional radiant heater (not shown) which is periodically
energized to defrost the evaporator 30 is also provided.
The refrigerator 20 also includes an air circulating system
comprising a fan 34, a passageway 36 for conducting a first stream
of air from the evaporator chamber 32 to the freezer compartment
24, a duct 38 for conducting a second stream of air from the
evaporator chamber 32 to the fresh food compartment 26, and
passageways 40 and 42 for conducting air from the two compartments
back to the evaporator chamber 32. Typically, the volume of the
first stream of air circulating through the freezer compartment 24
comprises approximately 90% of the total airflow through the
evaporator chamber 32, with the airflow through the fresh food
compartment 26 making up the remaining 10%.
In order to thermostatically maintain the desired temperature in
the fresh food compartment 26, a thermostatic temperature control
44 controls the operation of the compressor (not shown), and thus
energization of the evaporator 30, as needed. The thermostatic
control 44 comprises a temperature sensing element such as a
temperature sensing capillary 46 and an electrical switch (not
shown). A first user-operable control member 48, designated the
"fresh food control," is operatively connected to the thermostatic
control 44. In order to reduce customer complaints which might
arise if actual temperatures were indicated on the scale 50
associated with the control member 48, the scale 50 includes
arbitrary graduations 1 through 9, 1 being the warmest and 9 being
the coldest position.
Preferably, the refrigerated air conducted from the evaporator
chamber 32 through the duct 38 into the fresh food compartment 26
is discharged through a nozzle 52 into a mixing chamber 54 so
designed that a proportioned amount of fresh food compartment air
is drawn through an opening 56 into the mixing chamber 54 by the
aspirating effects induced by the air from the nozzle 52 and
becomes mixed therewith before the temperature is sensed by the
capillary 46 and before the air passes into the fresh food
compartment 26. It will be apparent therefore that, rather than
merely sensing the temperature of fresh food compartment air, when
the fan 34 is running, the temperature sensing capillary 46
associated with thermostatic control 44 actually senses the
temperature of a mixture of recirculated fresh food compartment air
and refrigerated air supplied to the fresh food compartment 26 from
the evaporator chamber 32. Such a system reduces the actual fresh
food compartment air temperature drop needed to turn the
thermostatic control 44 from "on" to "off," thereby maintaining the
fresh food temperature within closer limits than would otherwise be
possible. Since the temperature sensed by the capillary 46 is
related to the temperature in the fresh food compartment 26, for
the purposes herein, the phrase "for sensing temperature in the
fresh food compartment" is intended to include such a system.
Further details of the nozzle 52, the mixing chamber 54, and the
operation thereof are disclosed in the above-mentioned U.S. Pat.
No. 3,320,761--Gelbard.
In order to provide control over the air temperature in the freezer
compartment 24, an airflow damper 58 is positioned in the duct 38
and operatively connected to a user-operable control member 60. The
control member 60 is designated the "freezer control" and has
graduations A through E. To obtain a colder temperature in the
freezer compartment 14, the freezer control 60 is manually moved
towards the E position, causing the damper 58 to further restrict
airflow through the duct 38. Due to the resulting decreased
refrigerated air supply to the fresh food compartment 26, the
evaporator 30 is energized for a greater percentage of time to
satisfy cooling requirements of the fresh food compartment 26 to
maintain the temperature thereof. Energization of the evaporator 30
occurs, of course, whenever the thermostatic control 44 causes the
compressor to operate. Since the temperature within the freezer
compartment 24 primarily depends upon the percentage of time the
evaporator 30 is energized, the freezer temperature is lowered, as
desired.
Conversely, moving the freezer control 60 towards the A position
opens the damper 58 more, resulting in more refrigerated air from
the evaporator chamber 32 flowing through the duct 38 into the
fresh food compartment 26. This results in the evaporator being
energized less often or for shorter periods of time, causing a
higher freezer compartment temperature, as desired.
While only a single duct 38 and a single damper 58 are illustrated,
in certain refrigerators the duct 38 is divided into two parallel
ducts and a damper is included in each duct. The dampers operate
together so the effect is the same.
The indications associated with the position of the freezer control
60 and the damper 58 necessarily are not calibrated in temperature
because, in the prior art refrigerator 20, the actual temperature
in the freezer compartment 24 is also dependent upon the setting of
the fresh food control 48, as is explained in greater detail in the
"Background of the Invention."
Referring now to FIG. 2, exemplary temperature control
characteristic curves for the temperature control system in the
prior art refrigerator 20 described above with reference to FIG. 1
are graphically illustrated. The characteristic curves show the
temperatures to be expected in both the freezer compartment 24 and
the fresh food compartment 26 for various combinations of settings
of the fresh food control 48 and the freezer control 60. The
effects of the two controls are easily distinguished on the graph
because the fresh food control 48 has numbered graduations and the
freezer control 60 has lettered graduations. For example, if the
fresh food control 48 is set at 5 and the freezer control is set at
C, it can be determined, from the point designated 62, that the
temperature in the freezer compartment 24 is approximately
-1.degree. F and the temperature in the fresh food compartment 26
is approximately 34.degree. F. To graphically illustrate the
interaction of the fresh food temperature control 48 on the
temperature in the freezer compartment 24 in the prior art system,
consider an exemplary situation where the freezer control 60
remains set at C and the fresh food compartment temperature control
48 is moved from 5 to 1, calling for a warmer fresh food
temperature. The resulting control point is designated 64. As
desired, the temperature in the fresh food compartment 26 rises to
approximately 38.degree. F. Undesirably, the temperature in the
freezer compartment 24 also rises, up from -1.degree. F to
5.degree. F. It will be apparent from the curves shown in FIG. 2
that the interactive effect on the fresh food control 48 on the
temperature in the freezer compartment 24 is reflected on the graph
by the lines which slope downwardly and to the left beginning at
each of the letters A through E. Since the temperature in the fresh
food compartment 26 is more nearly maintained at any desired
temperature by thermostatic control action, there is very little
corresponding interaction of the setting of the freezer control 60
on the temperature in the fresh food compartment 26. This is
reflected on the graph by the substantially vertical lines
extending downwardly from each of the numbers 1, 3, 5, 7 and 9.
Referring to FIG. 3, an optimum temperature control characteristic
curve is illustrated. As can be seen in FIG. 3, desirably the
settings of the fresh food control 48 (represented by numbers 1, 3,
5, 7 and 9) affect only the temperature in the fresh food
compartment 26 and have no effect on the temperature in the freezer
compartment 24. Additionally, both the freezer compartment
temperature and the fresh food compartment temperature can be
varied over their entire respective ranges, regardless of the
setting of the other control member. By the present invention, such
a characteristic can be achieved. However, to achieve such a
characteristic would require a modification of the operating limits
or capabilities of the refrigeration system (including duct
configuration) in the prior art refrigerator 20. That such
modification would be required is evident from the different
general shapes of envelopes of the characteristic curves of FIGS. 2
and 3. For example, in FIG. 2, a freezer temperature of 5.degree. F
would be impossible to achieve at the same time the fresh food
temperature is set at 32.degree.. However, if the fresh food
temperature were set at 40.degree., a freezer temperature of
5.degree. would be within the capabilities of the refrigeration
system.
Referring now to FIG. 4, there is illustrated a temperature control
characteristic curve which is achieved by a preferred embodiment of
the present invention and which is within the operating limits or
capabilities of the refrigeration system of a particular prior art
refrigerator. In FIG. 4, the general shape of the curve envelope
shown in FIG. 2 is maintained, but the control characteristics are
quite different. In FIG. 4, the lines which begin at the freezer
temperature settings 12.degree., 6.degree., and 0.degree. extend
from these numbers substantially horizontally to the left,
indicating control independence. This is in contrast to FIG. 2 in
which the lines beginning at each of the letters A through E slope
downwardly and to the left, indicating control interaction.
Apparatus according to the present invention can be substituted
directly in place of the simple damper 58 controlled by the fresh
food control 60 of the prior art refrigerator 20 (FIG. 1),
resulting in substantially independent control over the freezer and
fresh food temperatures but remaining within the operating limits
or capabilities of the refrigeration system. Additionally,
preferred embodiments of the present invention indicate to the user
when the user attempts to set a combination of desired freezer and
fresh food compartment temperatures which is not within the
operating limits or capabilities of the refrigerator. An example of
such a combination, as discussed above, is a freezer temperature of
5.degree. F and a fresh food temperature of 40.degree. F.
Referring now to FIG. 5, there is shown the duct portion 38 of a
refrigerator and a functional schematic representation of the
present invention. FIG. 5 is intended to illustrate operational
principles of the present invention, and is not necessarily an
embodiment which would be constructed. It will be understood that
the duct 38 shown in FIG. 5 is similar to the duct 38 in the prior
art refrigerator 20 (FIG. 1) and conducts refrigerated evaporator
chamber air to the fresh food compartment 26. Other elements in the
refrigerator are the same as in the prior art refrigerator 20 and,
for convenience of illustration, are not shown. It will be
understood that the representation of FIG. 5 is in schematic form
only and various supporting and guiding members must be employed to
hold the various elements in their proper relative positions.
In FIG. 5, variable airflow control apparatus generally comprises
an adjustable air valve, such as a damper 66, operatively connected
to the output of a mechanical summer or differential, generally
designated at 68. As will be more apparent from the more detailed
description which follows, the arrangement is such that the degree
of damper opening and therefore airflow through the duct 38 is a
direct function of the temperature setting of the freezer control
60 and an inverse function of the temperature setting of the fresh
food control 48.
The mechanical summer 68 comprises a driven pinion gear 70 which
includes an axle 72. The axis of the pinion gear 70 and of the axle
72 is movable along a line shown as a broken line 74. In the
preferred embodiment of the invention, the line 74 is a straight
line and the movement of the axis is a translational movement.
The damper 66 is operatively attached to be driven by a slotted
yoke member 76, the slot 78 of the yoke being placed over the axle
72 for movement thereby. Movement of the axle 72 along the line 74
causes the slotted yoke member 76 and the damper 66 to rotate about
a pivot point 80, varying the degree of opening of the damper
66.
The mechanical summer 68 further includes first and second racks 82
and 84 having toothed faces 86 and 88 which engage the pinion gear
70 on diametrically opposite sides. The racks 82 and 84 also have
toothed faces 90 and 92 which engage first and second driving gears
94 and 96. To provide main and compensating inputs to the
mechanical summer 68, the driving gears 94 and 96 and connected
respectively to the freezer control 60 and the fresh food control
48 for rotation thereby. The connection of the gear 96 to the fresh
food control 48 is a ganged connection for operation along with the
thermostatic control 44.
In the operation of the embodiment illustrated in FIG. 5, manual
rotation of either the freezer control 60 or the fresh food control
48 causes the corresponding rack 82 or 84 to be longitudinally
displaced. Displacement of the rack 82 or 84 causes translation of
the axis of the pinion gear 70 and the axle 72. Resultant movement
of the slotted yoke member 76 causes movement of the damper 66 to
effect the desired change in airflow. For normal freezer
temperature control, for example, as the freezer control 60 is
rotated clockwise to call for a higher freezer temperature, the
rack 82 displaces to the right and the axis of pinion gear 70 and
the axle 72 translates to the right. This causes the yoke 76 and
the damper 66 to rotate counterclockwise about the pivot point 80,
opening the damper 66 more to permit increased airflow through the
duct 38. As previously explained, increased flow of refrigerated
evaporator chamber air through the duct 38 into the fresh food
compartment 26 indirectly causes the desired increase in freezer
temperature by decreasing the percentage of compressor and
evaporator run time.
Still considering the operation of the embodiment of FIG. 5, as the
fresh food control 48 is manually rotated clockwise, for example,
to call for a higher fresh food temperature, the compressor and
evaporator 30, under control of the thermoplastic control 44,
operate less frequently. Desirably, temperature in the fresh food
compartment 26 increases. If no compensation were provided, then,
undesirably, temperature in the freezer compartment 24 would also
be increased. However, due to the compensating input from the fresh
food control 48 to the second driving gear 96, the rack 84 is
displaced to the left and the axis of the pinion gear and axle 70
and 72 translates to the left. The yoke member 76 and the damper 66
rotate clockwise about the pivot point 80, further restricting duct
airflow. The further closing of the damper 66 in response to
clockwise rotation of the fresh food control 48 produces the same
result as a manual adjustment of the freezer control 60 to call for
a lower temperature would. Conversely, as the fresh food control 48
is manually rotated counterclockwise to call for a lower fresh food
temperature, the evaporator 30 operates more frequently and the
fresh food temperature desirably decreases. Counterclockwise
rotation of the second driving gear 96 causes displacement of the
rack 84 to the right and opening of the damper 66.
The compensation thus provided causes the freezer compartment
temperature to remain substantially constant despite changes in the
setting of the fresh food control 48. It will be apparent that the
design for a specific refrigerator requires a selection of the
proper gear diameters and ratios to achieve proper compensation,
but such selection is with the skill of one skilled in the art. In
the illustrated embodiment, the first driving gear 94 has a larger
diameter than the second driving gear 96.
Still referring to FIG. 5, in order to prevent a user from setting
the controls to a mutually exclusive pair of temperatures, movement
of the pinion gear axis is limited. This limitation may be
accomplished by selecting the length of the slot 78 or by including
limiting means in the guiding member (not shown). When a user
attempts to adjust one of the control members to a setting which,
in view of the setting of the other control member, would result in
a combination of temperatures outside the operating limits of the
refrigerator, the axis of the pinion gear 70 does not translate any
further because further movement is prevented. Instead, the pinion
gear 70 merely rotates about its axis causing longitudinal
displacement of the other rack and resulting rotation of the other
control member.
As a concrete example, assume that the freezer control 60 is set at
12.degree. and the fresh food control 48 is set at 41.degree..
Under this condition, the damper 66 is substantially completely
open and the pinion gear axis is translated as far to the right as
it will go. If the user now operates the fresh food control 48 to
call for a lower temperature to be maintained in the fresh food
compartment 26, and does not change the setting of the freezer
control 60, the user is attempting to call for a combination of
temperatures which is not within the operating limits of the
refrigerator. A reference to FIG. 4 will confirm this. When the
user rotates the fresh food control 48 counterclockwise, the second
rack 84 translates farther to the right. Since the pinion gear axis
cannot translate farther to the right, the pinion gear 70 rotates
counterclockwise about its axis, causing the first rack 82 to move
to the left. This causes the freezer control 60 to rotate
counterclockwise to a lower temperature setting, indicating to the
user that the combination of temperature settings he was trying to
get is not within the capabilities of the refrigerator.
In order to permit the fresh food control 48 and thus the
thermostatic control 44 to be rotated extremely clockwise to an OFF
position, the second driving gear 96 and the second rack 84 include
lost motion gearing. The lost motion gearing comprises a curved
extension 98 of the rack 84, which curved extension does not
include gear teeth. A corresponding portion 100 of the second
driving gear 96 is also devoid of gear teeth. When the fresh food
control 48 is rotated sufficiently clockwise, the portion 100 and
the curved extension 98 are in contact, permitting further
clockwise rotation of the control 48 without movement of the second
rack 84.
Referring now to FIG. 6, there is shown a rear perspective view of
a preferred embodiment of the present invention. The elements and
operation of FIG. 6 are substantially identical to those of FIG. 5,
and the corresponding elements are designated by identical
reference numerals. FIG. 6 differs from FIG. 5 in that the
arrangement of the parts is altered, but the operation is
substantially the same. A description of the operation is therefore
not repeated. In FIG. 6, airflow is from right to left across the
rear of the apparatus. For clarity of illustration, the direct
connection between the fresh flood control 48 and the thermostatic
control 44 is exploded. The shaft 102 of the thermostatic control
96 engages a corresponding opening 104 in the second driving gear
96. The first rack 82 (exploded illustration) which engages the
first driving gear 94 and the pinion 70 is short and has the gear
faces 86 and 90 located above one another. The second rack 82 which
engages the second driving gear 96 and the pinion gear 70 is
elongated, having the gear 88 and 92 at opposite ends.
Referring now to FIG. 7, there is shown an embodiment of the
present invention which permits the fresh food and freezer controls
48 and 60 to be rotatable and in axial alignment along a major
axis, shown as a broken line 106. In FIG. 7, it will be understood
that the damper 66 is disposed within a duct (not shown) which is
analogous to the duct 38 (FIG. 1). As indicated by the arrow 108,
the damper 66 is disposed within the duct in a manner such that, as
the damper 66 moves rearwardly, it opens more, allowing increased
flow of refrigerated evaporator chamber air into the fresh food
compartment 26; as the damper 66 moves forwardly, it closes more,
decreasing airflow into the fresh food compartment 26.
Conventionally, the fresh food control 48 is connected by a
rotatable shaft 110 to the thermostatic control 44 which maintains
the desired temperature in the fresh food compartment 26 by
energizing the evaporator 30 as required.
The mechanical summer 68 (FIG. 7) generally comprises a planetary
gear arrangement. A driving ring gear 112 is firmly attached to the
freezer control 60 for rotation thereby about the major axis 106. A
driving central gear 114 is located within the ring gear 112 and is
connected through a shaft 116 extending along the major axis 106
for rotation by the fresh food control 48. A portion 118 of the
shaft 116 is of reduced diameter for holding and for providing a
pivot for the damper 66. A driven pinion gear 120 engages both the
ring gear 112 and the central gear 114 and is attached to a
rotatable shaft or axle 122. The axis common to the pinion gear 120
and the shaft or axle 122 is movable in an arcuate path 124 about
the major axis 106. In order to provide an output for the summer
68, a pinion gear carrier 126 engages the shaft or axle 122 for
rotation about the pivot 118 in response to movement of the pinion
gear axis along the arcuate path 124. The pinion gear carrier 126
is connected to operate the damper 66.
It will be apparent that the position of the pinion gear axis along
the arcuate path 124 is a function of the settings of both of the
control members 48 and 60. The carrier 126 serves to cause a
corresponding degree of opening of the damper 66. As a result, the
flow of refrigerated evaporator chamber air into the fresh food
compartment 26 is the proper function of the settings of both
control members 48 and 60.
The operative of the embodiment illustrated in FIG. 7 will now be
explained. For normal freezer temperature control, as the freezer
control 60 is rotated clockwise (in the direction of the arrow) to
call for a colder freezer temperature, rotation of the ring gear
112 causes the axis of the pinion gear 120 to move clockwise along
the arcuate path 124. The pinion gear carrier 126 causes the damper
66 to pivot towards the closed position, decreasing airflow through
the duct. As previously explained, decreased flow of refrigerated
evaporator chamber air through the duct into the fresh food
compartment indirectly causes the desired decrease in freezer
temperature by increasing the percentage of compressor and
evaporator run time. Conversely, as the freezer control 60 is
rotated counterclockwise to call for a warmer freezer temperature,
the damper 66 pivots towards the open position.
Considering now the operation of the compensating feature of the
embodiment of FIG. 7, as the fresh food control 48 is rotated
counterclockwise (in the direction of the arrow) to call for a
colder fresh food temperature, the compressor and evaporator, under
control of the thermostatic control 44, operate more frequently.
Desirably, fresh food compartment temperature decreases. If no
compensation were provided, then, undesirably, freezer temperature
would also increase. However, counterclockwise rotation of the
central gear 114 causes the axis of the pinion gear 120 to move
counterclockwise along the arcuate path 124. The pinion gear
carrier 126 causes the damper 66 to pivot towards the open
position, increasing airflow through the duct. Conversely,
clockwise rotation of the fresh food control 48 to call for a
higher fresh food temperature results in decreased airflow through
the duct.
The present invention therefore provides a single evaporator,
single fan combination refrigerator which has substantially
independent fresh food and freezer temperature controls.
While specific embodiments of the invention have been illustrated
and described herein, it is realized that numerous modifications
and changes will occur to those skilled in the art. It is therefore
to be understood that the appended claims are intended to cover all
such modifications and changes as fall within the true spirit and
scope of the invention.
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